Dunno about outside (though 4br are usually about, their winners pics are shot outside) but there's a company that will offer to do you a photo as you come off stage, you walk through the trade stands on your way back to the changing rooms and they're there. Can't remember the company name though!

The photos taken last year as bands came off stage were pretty good - full band, sections and individual players. The guys there were pretty busy, though, and had a lot of gear so I'm not sure they'd be up for going outside.